<?php
/**
* Global Search Engine for Moodle
*
* @package search
* @category core
* @subpackage document_wrappers
* @author Valery Fremaux [valery.fremaux@club-internet.fr] > 1.8
* @date 2008/03/31
* @license http://www.gnu.org/copyleft/gpl.html GNU Public License
*
* document handling for chat activity module
* This file contains the mapping between a chat history and it's indexable counterpart,
*
* Functions for iterating and retrieving the necessary records are now also included
* in this file, rather than mod/chat/lib.php
*
*/

/**
* includes and requires
*/
require_once("$CFG->dirroot/search/documents/document.php");
require_once("$CFG->dirroot/mod/chat/lib.php");

/**
* a class for representing searchable information
* 
*/
class ChatTrackSearchDocument extends SearchDocument {

	/**
	* constructor
	*/
	public function __construct(&$chatsession, $chat_id, $chat_module_id, $course_id, $group_id, $context_id) {
		// generic information; required
		$doc->docid		 = $chat_id.'-'.$chatsession['sessionstart'].'-'.$chatsession['sessionend'];
		$doc->documenttype  = SEARCH_TYPE_CHAT;
		$doc->itemtype	  = 'session';
		$doc->contextid	 = $context_id;

		$duration		   = $chatsession['sessionend'] - $chatsession['sessionstart'];
		// we cannot call userdate with relevant locale at indexing time.
		$doc->title		 = get_string('chatreport', 'chat').' '.get_string('openedon', 'search').' TT_'.$chatsession['sessionstart'].'_TT ('.get_string('duration', 'search').' : '.get_string('numseconds', '', $duration).')';
		$doc->date		  = $chatsession['sessionend'];
		
		//remove '(ip.ip.ip.ip)' from chat author list
		$doc->author		= preg_replace('/\(.*?\)/', '', $chatsession['authors']);
		$doc->contents	  = $chatsession['content'];
		$doc->url		   = chat_make_link($chat_module_id, $chatsession['sessionstart'], $chatsession['sessionend']);
		
		// module specific information; optional
		$data->chat		 = $chat_id;
		
		// construct the parent class
		parent::__construct($doc, $data, $course_id, $group_id, 0, 'mod/'.SEARCH_TYPE_CHAT);
	} 
}


/**
* constructs a valid link to a chat content
* @param cm_id the chat course module
* @param start the start time of the session
* @param end th end time of the session
* @uses CFG
* @return a well formed link to session display
*/
function chat_make_link($cm_id, $start, $end) {
	global $CFG;

	return $CFG->wwwroot.'/mod/chat/report.php?id='.$cm_id.'&amp;start='.$start.'&amp;end='.$end;
}

/**
* fetches all the records for a given session and assemble them as a unique track
* we revamped here the code of report.php for making sessions, but without any output.
* note that we should collect sessions "by groups" if groupmode() is SEPARATEGROUPS.
* @param int $chat_id the database
* @param int $fromtime
* @param int $totime
* @uses CFG
* @return an array of objects representing the chat sessions.
*/
function chat_get_session_tracks($chat_id, $fromtime = 0, $totime = 0) {
	global $CFG;
	
	$chat = get_record('chat', 'id', $chat_id);
	$course = get_record('course', 'id', $chat->course);
	$coursemodule = get_field('modules', 'id', 'name', 'data');
	$cm = get_record('course_modules', 'course', $course->id, 'module', $coursemodule, 'instance', $chat->id);
	$groupmode = groupmode($course, $cm);

	$fromtimeclause = ($fromtime) ? "AND timestamp >= {$fromtime}" : ''; 
	$totimeclause = ($totime) ? "AND timestamp <= {$totime}" : ''; 
	$tracks = array();
	$messages = get_records_select('chat_messages', "chatid = '{$chat_id}' $fromtimeclause $totimeclause", "timestamp DESC");
	if ($messages){
		// splits discussions against groups
		$groupedMessages = array();
		if ($groupmode != SEPARATEGROUPS){
			foreach($messages as $aMessage){
				$groupedMessages[$aMessage->groupid][] = $aMessage;
			}
		} else {
			$groupedMessages[-1] = &$messages;
		}
		$sessiongap = 5 * 60;	// 5 minutes silence means a new session
		$sessionend = 0;
		$sessionstart = 0;
		$sessionusers = array();
		$lasttime = time();
	
		foreach ($groupedMessages as $groupId => $messages) {  // We are walking BACKWARDS through the messages
			$messagesleft = count($messages);
			foreach ($messages as $message) {  // We are walking BACKWARDS through the messages
				$messagesleft --;			  // Countdown
	
				if ($message->system) {
					continue;
				}
				// we are within a session track
				if ((($lasttime - $message->timestamp) < $sessiongap) and $messagesleft) {  // Same session
					if (count($tracks) > 0){
						if ($message->userid) {	   // Remember user and count messages
							$tracks[count($tracks) - 1]->sessionusers[$message->userid] = $message->userid;
							// update last track (if exists) record appending content (remember : we go backwards)
						}
						$tracks[count($tracks) - 1]->content .= ' '.$message->message;
						$tracks[count($tracks) - 1]->sessionstart = $message->timestamp;
					}
				} else {
				// we initiate a new session track (backwards)
					$track = new Object();
					$track->sessionend = $message->timestamp;
					$track->sessionstart = $message->timestamp;
					$track->content = $message->message;
					// reset the accumulator of users
					$track->sessionusers = array();
					$track->sessionusers[$message->userid] = $message->userid;
					$track->groupid = $groupId;
					$tracks[] = $track;
				} 
				$lasttime = $message->timestamp;
			} 
		} 
	} 
	return $tracks;
}

/**
* part of search engine API
*
*/
function chat_iterator() {
	$chatrooms = get_records('chat');
	return $chatrooms;
}

/**
* part of search engine API
*
*/
function chat_get_content_for_index(&$chat) {
	$documents = array();
	$course = get_record('course', 'id', $chat->course);
	$coursemodule = get_field('modules', 'id', 'name', 'chat');
	$cm = get_record('course_modules', 'course', $chat->course, 'module', $coursemodule, 'instance', $chat->id);
	if ($cm){
		$context = get_context_instance(CONTEXT_MODULE, $cm->id);
	
		// getting records for indexing
		$sessionTracks = chat_get_session_tracks($chat->id);
		if ($sessionTracks){
			foreach($sessionTracks as $aTrackId => $aTrack) {
				foreach($aTrack->sessionusers as $aUserId){
					$user = get_record('user', 'id', $aUserId);
					$aTrack->authors = ($user) ? fullname($user) : '' ;
					$documents[] = new ChatTrackSearchDocument(get_object_vars($aTrack), $chat->id, $cm->id, $chat->course, $aTrack->groupid, $context->id);
				}
			}
		}
		return $documents;
	}
	return array();
}

/**
* returns a single data search document based on a chat_session id
* chat session id is a text composite identifier made of :
* - the chat id
* - the timestamp when the session starts
* - the timestamp when the session ends
* @param id the multipart chat session id
* @param itemtype the type of information (session is the only type)
*/
function chat_single_document($id, $itemtype) {
	list($chat_id, $sessionstart, $sessionend) = split('-', $id);
	$chat = get_record('chat', 'id', $chat_id);
	$course = get_record('course', 'id', $chat->course);
	$coursemodule = get_field('modules', 'id', 'name', 'chat');
	$cm = get_record('course_modules', 'course', $course->id, 'module', $coursemodule, 'instance', $chat->id);
	if ($cm){
		$context = get_context_instance(CONTEXT_MODULE, $cm->id);
	
		// should be only one
		$tracks = chat_get_session_tracks($chat->id, $sessionstart, $sessionstart);
		if ($tracks){
			$aTrack = $tracks[0];
			$document = new ChatTrackSearchDocument(get_object_vars($aTrack), $chat_id, $cm->id, $chat->course, $aTrack->groupid, $context->id);
			return $document;
		}
	}
	return null;
}

/**
* dummy delete function that packs id with itemtype.
* this was here for a reason, but I can't remember it at the moment.
*
*/
function chat_delete($info, $itemtype) {
	$object->id = $info;
	$object->itemtype = $itemtype;
	return $object;
}

/**
* returns the var names needed to build a sql query for addition/deletions
* // TODO chat indexable records are virtual. Should proceed in a special way 
*/
function chat_db_names() {
	//[primary id], [table name], [time created field name], [time modified field name]
	return null;
}

/**
* this function handles the access policy to contents indexed as searchable documents. If this 
* function does not exist, the search engine assumes access is allowed.
* When this point is reached, we already know that : 
* - user is legitimate in the surrounding context
* - user may be guest and guest access is allowed to the module
* - the function may perform local checks within the module information logic
* @param path the access path to the module script code
* @param itemtype the information subclassing (usefull for complex modules, defaults to 'standard')
* @param this_id the item id within the information class denoted by entry_type. In chats, this id 
* points out a session history which is a close sequence of messages.
* @param user the user record denoting the user who searches
* @param group_id the current group used by the user when searching
* @uses CFG
* @return true if access is allowed, false elsewhere
*/
function chat_check_text_access($path, $itemtype, $this_id, $user, $group_id, $context_id){
	global $CFG;
	
	include_once("{$CFG->dirroot}/{$path}/lib.php");

	list($chat_id, $sessionstart, $sessionend) = split('-', $this_id);
	// get the chat session and all related stuff
	$chat = get_record('chat', 'id', $chat_id);
	$context = get_record('context', 'id', $context_id);
	$cm = get_record('course_modules', 'id', $context->instanceid);
	// $cm = get_coursemodule_from_instance('chat', $chat->id, $chat->course);
	// $context = get_context_instance(CONTEXT_MODULE, $cm->id);

	if (!$cm->visible and !has_capability('moodle/course:viewhiddenactivities', $context)){
		if (!empty($CFG->search_access_debug)) echo "search reject : hidden chat ";
		return false;
	}
	
	//group consistency check : checks the following situations about groups
	// trap if user is not same group and groups are separated
	$course = get_record('course', 'id', $chat->course);
	if ((groupmode($course, $cm) == SEPARATEGROUPS) && !ismember($group_id) && !has_capability('moodle/site:accessallgroups', $context)){ 
		if (!empty($CFG->search_access_debug)) echo "search reject : chat element is in separated group ";
		return false;
	}

	//ownership check : checks the following situations about user
	// trap if user is not owner and has cannot see other's entries
	// TODO : typically may be stored into indexing cache
	if (!has_capability('mod/chat:readlog', $context)){
		if (!empty($CFG->search_access_debug)) echo "search reject : cannot read past sessions ";
		return false;
	}
		
	return true;
}

/**
* this call back is called when displaying the link for some last post processing
*
*/
function chat_link_post_processing($title){
	global $CFG;
	setLocale(LC_TIME, substr(current_language(), 0, 2));
	$title = preg_replace('/TT_(.*)_TT/e', "userdate(\\1)", $title);
	
	if ($CFG->block_search_utf8dir){
		return mb_convert_encoding($title, 'UTF-8', 'auto');
	}
	return mb_convert_encoding($title, 'auto', 'UTF-8');
}
?>